Pomona College Jouknai, of Entomology 853 



DIK IIALTERKN DKli DII'TEREN 



IinOO PKLUGSTAEDT 



Zcit. r. Wiss. Zool. U(l. ('., II.. 1, lf)12. 



This is a carcfiil anatomical study of the lialtercs of several species of 

 flies; Sarcophaga carmaria, CalUphora enjthrorrphala, Syrphuf: balteatus and 

 Eristalis temox. 



The nerves going to the halteres arc from the liiird thoracic ganglion, or 

 from that part of the fused thoracic central nervous system whicli would 

 correspond to the third ganglion. The nerve is as large or larger tlian the 

 other nerve which goes to the wings (Figure 271). Figure 271, A, is a copy 

 from the author's drawing of tliis organ in Erixtalis, from the dorsal side. 

 Figure 271, B, is from tiie ventral side. There are three main regions, the 

 base, the stalk and the head. On the dorsal side of the base are two patches 

 of sensory structures and one similar one on the ventral side. In the liead 

 is a furrow, and on it a few sensory hairs of the usual type. 



The author recognizes three types of sensory organs: (1) papilla>, such as 

 those at the base of the organ; (2) sense hairs, such as those on the head; 

 (3) chordotonal organs. These last lie under the ventral chitinous plate on 

 the basal part of the organ (Figure 271, B). 



The nerves which enter the halteres are large and seem to be entirely 

 sensory although coming off from the lower part of the thoracic ganglionic 

 mass, they have a rather direct patliwa.v through the ganglion to the con- 

 nectives which run to the subesophageal ganglion, as is shown in the copy of 

 the author's figure of a longitiulinal section through the ganglion (P"'igure 

 271, C and D). 



The nerve on each side divides into two upon entering the sensory 

 structure and the smaller one on the ventral side supplies some sen.se organs 

 on that side. The larger nerve is connected witli sensory terminations on 

 each .side (Figure 271, E). There is a cliitinous mass [lartly separating the.se 

 two nerves. 



Of the basal papilhp, the author ma]<es two types, one .sort where the 

 nerves end in sliglit elevations, and the kind where there are almost no 

 elevations of the chitin. 



The chordotonal organs are similar to those found in other locations 

 among insects but seem to be not complete enough to be organs of hearing. 

 As to the function of the iiapilla' and other sense organs, the author is still in 

 doubt. By some they have been considered to be olfactory organs, but the 

 author does not favor this because he tliinks their structure is not enough 

 like tliose well known in other artliro|)ods. lie tliinks it possil)le that the 

 cliortlotonal organs maj' be for detecting strain and stress, i)erliMps sometliing 

 like a muscular sense. Similar sense organs as tiiose found in tiic halteres 

 occur in the wings of insects. 



Some experiments were performed with living tiies. When both iialteres 

 were removed the insects were unable to fly, and if thrown into the air fell 



